400. That’s an error.

Google cannot redirect you to http://worldcat.org/search?q=works+Alexander+Pope.+his+last+corrections,+additions,+improvements;+together+all+his+notes:+pr.+verbatim+octavo+ed.+mr.+Warburton+alexander+pope because the request was invalid.

This might be because the link was created a long time ago. Try your search again on Google. That’s all we know.